SUMMARYFor increased bandwidth efficiency and receiver performance, standards for satellite broadcasting systems are evolving by utilizing efficient transmission techniques. The second-generation digital video broadcasting for satellites (DVB-S2) adopts the amplitude phase shift keying (APSK) modulation for enhanced performance over nonlinear channels. In this paper, we derive error rate bounds for APSK modulated symbols and generalize the bounds to the case of distorted constellation, which occurs when the maximum transmission amplitude is saturated by the soft-limiter type channel. The derived bound is shown to significantly improve the previously known result, to accurately predict both the symbol error rate and bit error rate in the entire signal-to-noise ratio (SNR) region of interest. Using the derived formula, the optimal input power level for the soft-limiter channel is determined, and the corresponding minimal error rates for 16-and 32-APSK are quantified. The result is also interpreted in terms of optimal input back-off (IBO) for nonlinear power amplifiers by evaluating the performance degradation as a function of IBO.

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This paper presents the satellite orthogonal frequency division multiplexing (SAT-OFDM) technology as a satellite radio interface for international mobile telecommunications (IMT)-Advanced. The SAT-OFDM radio interface is designed to provide various advanced IMT services in satellite environments. For cost-effective deployment of a satellite IMT-Advanced system, the radio interface must have a high degree of commonality with third-generation partnership project long-term evolution (3GPP LTE) technology for IMT-Advanced, but it also has a number of different features. Those features are needed to adapt the 3GPP LTE technology for satellite-specific environments such as long round-trip delay, large cell size, and slow-fading satellite channel. In this paper, we summarize the key features of the SAT-OFDM technology and propose satellite specific features included in the SAT-OFDM technology as an adaption way of LTE over satellite. Then we show the performance evaluation results of the SAT-OFDM technology to see the feasibility of LTE over satellite. communication with space stations cannot be guaranteed [2]. The CGCs will provide more efficient spectrum usage, and the improved coverage would further attract large consumer markets, resulting in increased economies of scale. This will reduce the costs of producing handheld terminals and the overall price of services to end users, ensuring reduced cost of the satellite IMT in remote areas. In many regions, satellite IMT operators are allowed to deploy CGCs in order to improve service coverage. Broadband services can be provided to single-mode user equipment (UE), that is, quasi-terrestrial IMT UE, through a satellite and the CGC operating within the satellite frequency bands [3].In such integrated satellite IMT systems, one of the key issues is how to optimize the spectral efficiency of the mobile satellite service (MSS) system as a whole (satellite plus CGC). CGCs are different from the independent ground components used in the mobile systems, as they are technically and operationally an integral part of the satellite system and are controlled by the common resource and network management mechanism of such a system operating in the same frequencies as the associated satellite components and are delivered to integrated user equipment. The frequency reuse between the satellite and CGCs will inevitably imply co-channel interference, which might degrade the performance of the MSS system. Service scenarios and a flexible frequency reuse scheme are effective means for optimized spectrum utilization between the satellite and CGC [4]. In addition, intelligent resource allocation and interference management techniques can be utilized [5,6].The satellite radio interface for IMT-Advanced may support flexible carrier bandwidth and dynamic resource and interference management for integrated satellite IMT systems. The other key issue is the implementation of a single cost-effective UE supporting both the satellite and the CGC by possibly reusing terrestrial IMT-Advanced UE. In that...